Clarella Howell, 1933

Unger, Tanja, Hildenbrand, Anne, Stinnesbeck, Wolfgang & Austermann, Gregor, 2022, Biostratigraphy and taxonomy of polymerid trilobites of the Manuels River Formation (Drumian, middle Cambrian), Newfoundland, Canada, Geodiversitas 44 (33), pp. 1051-1087 : 1075

Genus Clarella Howell, 1933

Clarella Howell, 1933: 219 . —

Type species: Anapolenus venustus Billings, 1872 , designated as lectotype by Howell (1933).

DIAGNOSIS. — Glabella with great forward expansion anterior of S1; palpebral lobes slightly sigmoidal, reaching almost genal angle; thorax with 15 segments; pygidium without border, up to four pairs of marginal spines; short axis with one to two axial rings (based on Howell 1933; Whittington et al. 1997, with modifications).

REMARKS

Clarella is distinguished from Anapolenus Salter, 1864a by sigmoidally shaped palpebral lobes that almost reach the genal angle. The palpebral lobes of Anapolenus curve in a uniform arc, reaching the genal angle. The pygidium of Clarella lacks a border, while that of Anapolenus is bordered ( Howell 1933; Whittington et al. 1997).